Color photographic developing solutions containing aromatic primary amine color developing agents have long been conventionally used in the formation of color images, and now have a major role in the color photographic image formation process. However, it is well known that conventional color developing solutions are easily oxidized by air or metals, and that if the developing solutions thus oxidized are used to form a color image, fogging increases, sensitivity or gradation changes, and therefore photographic characteristics are adversely affected.
Therefore, various measures to improve the preservability of color developing solutions have been studied, and use of a combination of hydroxylamine and a sulfite ion is the most general current practice. However, when hydroxylamine decomposes, ammonia is released, which causes fogging, and a sulfite ion acts as a competing compound against developing agents, for example, to disadvantageously reduce their color formation capability, so that neither is a preferred preservative.
Particularly, although a sulfite ion has been used as a compound to improve the preservability of various developing agents or to prevent decomposition of hydroxylamine, it greatly impedes color development, and when it is used in a system without benzyl alcohol (which is disadvantageous from the point of view of environmental pollution and preparation of a developing solution), the developed color density is significantly lowered.
Alkanolamines described in Japanese patent application (OPI) No. 3532/79 (corresponding to U.S. Pat. No. 4,170,478) (the term "OPI" as used herein refers to a "published unexamined Japanese patent application") and polyethyleneimines described in Japanese Patent Application (OPI) No. 94349/81 (corresponding to U.S. Pat. No. 4,252,892) are suggested as compounds that can be substituted for sulfites, but these compounds remain unsatisfactory.
Conventionally, to improve the stability of color developing solutions, various preservatives and chelating agents have been studied. For example, preservatives include aromatic polyhydroxy compounds described in Japanese patent application (OPI) Nos. 49828/77, 160142/84 and 47038/81 (corresponding to U.S. Pat. No. 4,264,716) and U.S. Pat. No. 3,746,544; hydroxycarbonyl compounds described in U.S. Pat. No. 3,615,503 and British Pat. No. 1,306,176; .alpha.-aminocarbonyl compounds described in Japanese patent application (OPI) Nos. 143020/77 (corresponding to U.S. Pat. No. 4,155,764) and 89425/78; metal salts described in Japanese Patent Application (OPI) Nos. 44148/82 (corresponding to U.S. Pat. No. 4,330,616) and 53749/82; and hydroxamic acids described in Japanese patent application (OPI) No. 27638/77 (corresponding to U.S. Pat. No. 4,055,426). Chelating agents include aminopolycarboxylic acids described in Japanese Patent Publication Nos. 030496/73 and 30232/69 (corresponding to U.S. Pat. No. 3,462,269); organic phosphonic acids described in Japanese Patent Application (OPI) No. 97347/81, Japanese Patent Publication No. 39359/81 (corresponding to U.S. Pat. No. 3,794,591) and West German Patent 2,227,639; phosphonocarboxylic acids described, for example, in Japanese Patent Application (OPI) Nos. 102726/77 (corresponding to U.S. Pat. No. 4,083,723), 42730/78, 121127/79, 126241/80 and 65956/80 and compounds described, for example, in Japanese patent application (OPI) Nos. 195845/83 (corresponding to U.S. Pat. No. 4,482,626) and 203440/83 and Japanese Patent Publication No. 40900/78.
However, even if these techniques are used, preservative performance is inadequate, or photographic characteristics are adversely affected, so that satisfactory results have not yet been attained, and excellent preservatives that can be substituted for sulfites are still keenly sought.
In the case of color photographic materials containing a silver chlorobromide emulsion with a high chlorine content, fogging is liable to occur during color development as described in Japanese patent application (OPI) Nos. 95345/83 and 232342/84. When such an emulsion is used, it is essential to use a preservative that dissolves the emulsion to a reduced extent and has better preservability, and satisfactory preservatives from this viewpoint have not been found.